1. Field of the Invention
This invention relates to a structure of a brake pedal apparatus for vehicle, that is, relates to a brake pedal structure for a vehicle.
2. Description of the Related Art
A brake pedal apparatus for a vehicle is, as shown in Japanese Utility Model Application Laid-Open No. 6-1113, structured such that a pedal bracket supporting an upper end portion of a pedal arm in a freely rotatable manner is fastened to a dash lower panel and a lower surface portion of a dash upper panel connected to the dash lower panel and projecting to a vehicle cabin, and that a push rod connected to the upper end portion of the pedal arm is forward pressed when a driver steps on the pedal arm, thereby operating a Master vac.
When the Master vac or the dash lower panel fixing the Master vac is deformed so as to be backward moved toward the vehicle cabin at a time of a front collision of the vehicle, a rotational force in a direction inverse to a stepping direction of the pedal arm is operated on the pedal arm through the push rod of the Master vac. Accordingly, a stepping position of the pedal arm is rearward shifted and there may be a case that a feeling of physical disorder is generated for the driver.
An object of the present invention is to provide a brake pedal structure for a vehicle which allows to substantially prevent a collision load from operating on a pedal arm through a push rod typically connected to a Master vac at a time of a front collision of a vehicle so that a driver of the vehicle may not feel physical disorder.
To achieve the above object, a brake pedal structure for a vehicle according to the present invention basically comprises: a pedal bracket provided on a dash panel of the vehicle; a pedal shaft provided on the pedal bracket; a pedal arm pivotally supported by the pedal shaft in a freely rotatable manner around the pedal shaft as a rotational axis; and a push rod connected to the pedal arm for operating a brake system of the vehicle in response to rotation of the pedal arm. Here, this push rod includes a portion so as to interrupt the transmission of a load input at the time of collision of the vehicle.
With this structure, in a normal state, a stepping force is transmitted to a brake system through the push rod by stepping operation of the pedal arm, and a brake operation as in a general brake pedal structure can be conducted. Further, when the push rod retreats due to a head-on collision of the vehicle, the push rod efficiently interrupts the transmission of the load input and thus, it is possible to prevent the collision load from being substantially applied to the pedal arm.
More specifically, the brake pedal structure for a vehicle of the present invention further comprises a connection portion between the pedal arm and the push rod. This connection portion is disposed at a position offset from an arm portion of the pedal arm in a widthwise direction of the vehicle. Also, the push rod is provided at an end of the connection portion rearward of the vehicle with a pin member, and the connection portion comprises a notch, which opens downward of the vehicle and engages the pin member of the push rod to connect the pedal arm and the push rod with each other, and a projection, which is provided on an end of the connection portion forward of the vehicle. Here, the projection of the connection portion pushes the push rod downward of the vehicle to release the engagement of the notch of the connection portion and the pin member of the push rod when a load input in a rearward direction of the vehicle is applied to the connection portion through the push rod at the time of a collision of the vehicle.
With this structure, when the push rod retreats due to the head-on collision of the vehicle, since the push rod is moved downward of the vehicle so as to be disengaged, the transmission of the load input can reliably be interrupted. Further, even after the push rod is disengaged, since the connection portion between the pedal arm and the push rod is disposed at a position offset from the arm portion of the pedal arm in the widthwise direction of the vehicle, it is possible to prevent the push rod from interfering with the arm portion of the pedal arm, and since the push rod is pushed downward, it is possible to prevent the push rod from interfering with other peripheral parts such as the steering member.
Here, it is preferable that the connection portion is a push rod lever integrally connected to the pedal arm. This is because that the offset distance between the connection portion and the arm portion of the pedal arm can be secured sufficiently, and after the push rod is separated, it is possible to reliably prevent the push rod from interfering with the arm portion of the pedal arm.
Further, the opening of the notch of the connection portion includes a pin-drop-preventing portion by which the pin member can separate from the notch when a load input from the pin member which slides in a downward direction of the vehicle exceeds a predetermined value at the time of the collision of the vehicle.
In the case that this structure is employed, as long as the collision load transmitted through the push rod does not exceed the predetermined value due to the head-on collision of the vehicle, the pin-drop-preventing portion can prevent the push rod from being separated, and it is possible to enhance the reliability of the normal state.
Further, it is preferable that the opening of the notch of the connection portion opens downward and forward of the vehicle. When the brake pedal is stepped in the normal state, the notch and the pin member at the rear end of the push rod are engaged with each other deeper as the brake pedal is stepped stronger and therefore, the engagement is not released. However, when the push rod retreats at the time of the head-on collision of the vehicle, the engagement becomes shallower and is prone to be disengaged. Therefore, it is possible to enhance both reliability of the normal state and reliability at the time of collision.
Further, an end of the push rod rearward of the vehicle may be preferably connected to the pedal arm, the pedal arm may be preferably provided at its end forward of the vehicle with a projection. And in such a structure, the pedal arm push the push rod downward of the vehicle to bend the push rod when a load input in a rearward direction of the vehicle is applied to the pedal arm through the push rod at the time of a collision of the vehicle.
With this structure, in a normal state, a stepping force is transmitted to a brake system through the push rod by stepping operation of the pedal arm, and a brake operation as in a general brake pedal structure can be conducted. Further, when the push rod retreats due to a head-on collision of the vehicle, the push rod interrupts the transmission of the load input, it is possible to prevent the collision load from being applied to the pedal arm.
It is also preferable that the push rod includes an easily-bendable portion which is bent if the push rod receives a load input acting in a direction other than an axial direction of the push rod.
Since the easily-bendable portion is provided, when the push rod is pushed down and bent by the projection provided at the front end of the pedal arm, it is possible to further easily bend and deform the push rod, and to reliably prevent the collision load from being applied to the pedal arm.
Here, it is preferable that the projection of the pedal arm abuts against the push rod in the vicinity of the easily-bendable portion when a load input in a rearward direction of the vehicle is applied to the pedal arm through the push rod at the time of the collision of the vehicle. Because the push rod can be bent and deformed more reliably, and it is possible to prevent the collision load from being applied to the pedal arm.
Further, if the structure in which the push rod is bent is employed, it is preferable that the projection of the pedal arm is provided at an end thereof downward of the vehicle with a push rod catching portion extending in a widthwise direction of the vehicle. With this structure, it is possible to surely bend and deform the push rod downward, and to enhance the reliability.
In addition, it is preferable that the push rod is connected to a Master vac of the vehicle because smooth and reliable braking operation in the normal state can be ensured.